Teens’ IQs can rise (or fall), thanks to changes in the brain

During adolescence, changes in two regions of the brain have been linked to …

Here’s some good news for the parents of adolescents: if your teenager seems like a bit of a dud in the intelligence department, it’s possible that he or she isn’t doomed to a life of intellectual failure. On the flip side, however, kids who show early signs of high intelligence may not fare as well as you think they will. This information comes from a new study in Nature that shows that IQ is surprisingly variable during the teenage years, and that these changes are associated with specific changes in brain structure.

Over the course of the study, a group of 33 teenagers were given 2 IQ tests: one during early adolescence, and other in late adolescence. Both relied on the commonly used Weschsler intelligence tests. At the time of each IQ test, each teenager had a structural brain scan with an MRI machine. None of the participants knew they would be called back for a second test a few years later.

In each test, the subjects' IQ scores varied greatly, ranging from 77 to 135 during the first test, and 87 to 143 during the second. IQs are split into two types of scores: verbal IQ, which relates to verbal tasks, and performance IQ, which measures abilities such as logic and reasoning.

When called back for their second test, many of the subjects scored very differently on the IQ tests than they had the first time. Nearly 40 percent had different verbal IQ scores, and 21 percent had different performance IQ scores. Some teens scored lower and some scored higher than they had the first time; there was no correlation between the changes in verbal and performance IQ scores.

The researchers then compared these changes to differences between the two MRI scans for each subject. They found that the teens that had large changes in IQ scores between the two tests also had definite changes in their brain structure. Even more intriguingly, each type of score was related to changes in a different region.

Changes in verbal IQ were associated with changes in grey matter density in the left motor cortex, an area associated with speech. This area is activated by tasks such as reading and reciting numbers. Changes in performance IQ, on the other hand, were correlated with changes in grey matter density in the anterior cerebellum, which is responsible for hand movements. In the study, tasks that involve pressing a button activated this region of the brain.

From these results, it appears that very different types of IQ scores are closely linked to different sensorimotor skills. These abilities seem particularly apt to change over adolescence, as various structures in the brain develop. Densities of these brain regions could explain between 13 and 20 percent of the differences in the subsequent test scores, so clearly there must be other things going on.

Of course, IQ is just a number, and an individual's performance on a test can’t fully reflect their ability and potential. However, scientists still regard IQ scores as the best proxy we have for general intelligence. More research needs to be done to determine whether changes in these IQ scores are evident in other measures of performance, and whether they affect individuals’ education or employment history. Even more importantly, we don’t yet know why some teenagers' scores improved and others fell, so you can’t yet be sure what will happen to your children’s IQs as they pass through adolescence.

The striking fact about these studies is the tiny amount of experimental data. Anyone who thinks they can make wild generalizations about a subject as complicated as the development of human intelligence based on two tests of thirty three subjects is mainly demonstrating the limitations of their intelligence.

One thing researchers may not get is that if you give a high school student a test, and you ask them to take it seriously... they won't. This is even true of college students. When I was in high-school and college I know other students just blew tests like these off.

Correlating brain read-outs with IQ in adolescence and concluding those read-outs are causative in differences in IQ, even among individuals, may be a mistake. Every part of a persons body undergoes changes during adolescence, including the brain, do we know enough about the brain to conclude that those brain changes caused an increase (or decrease) in IQ.

Also we don't know enough about IQ to even conclude its a legitimate concept. This can explain how a students IQ dropped, or increased, in a few years, large variations in IQ is something researchers have been saying for decades is not possible. I don't think psychologists are able to quantify someones intelligence with a singular number, using a singular test.

Good heavens, is 130 really all it takes to get into Mensa? That explains a bit.

I went to a Mensa meeting once when I was considering joining. My IQ is well above the requisite 130, and it sounded like it would be interesting to converse with a really intelligent group of people. I found that Mensa is less an organization for the exchange of ideas between exceptionally intelligent people and more a club for people who like other people to know that they're exceptionally intelligent. I passed.

Good heavens, is 130 really all it takes to get into Mensa? That explains a bit.

I went to a Mensa meeting once when I was considering joining. My IQ is well above the requisite 130, and it sounded like it would be interesting to converse with a really intelligent group of people. I found that Mensa is less an organization for the exchange of ideas between exceptionally intelligent people and more a club for people who like other people to know that they're exceptionally intelligent. I passed.

I've known one Mensa member. He was bright, but not exceptionally so. He seemed to like to talk about being a Mensa member quite a bit.

Good heavens, is 130 really all it takes to get into Mensa? That explains a bit.

I went to a Mensa meeting once when I was considering joining. My IQ is well above the requisite 130, and it sounded like it would be interesting to converse with a really intelligent group of people. I found that Mensa is less an organization for the exchange of ideas between exceptionally intelligent people and more a club for people who like other people to know that they're exceptionally intelligent. I passed.

I've known one Mensa member. He was bright, but not exceptionally so. He seemed to like to talk about being a Mensa member quite a bit.

And therefore you know all Mensa members. See the earlier comments about small sample size.

I think something like Mensa should be for 140 and up, 130 is rare, but not particularly uncommon. That said, I've heard the average PhD is usually around 120-125, who knows if that is accurate or not.

It is not just teens. As I have been saying for years the brain is like a muscle in that if you work it out, it gets stronger; if you do not, it gets weaker. Using myself as a guinea pig I have found that I have a 20 point swing between when I have a job where I turn off my brain and when I have one where I get paid to think.

Give me a cattle prod and some IQ test books, riddles, puzzles, etc and I figure I could put 20 points on most people in a few months.

I think something like Mensa should be for 140 and up, 130 is rare, but not particularly uncommon. That said, I've heard the average PhD is usually around 120-125, who knows if that is accurate or not.

Mensa decided from the beginning to focus on the 98th percentile, which is 132 or so. There are other organizations that have higher thresholds for entry than Mensa. Triple-Nine (148), Prometheus (164), and Mega (176) are three I know of.

Sample size is a bit low but not alarmingly so imo; it would therefore be interesting to see the test repeated independently.

IQ, as we all know, is strongly heritable (0.5 to 0.8 as far as I can remember) and not likely to change over lifetime. Nature rather than nurture in other words. However, there seems to be some evidence that a very particular type of training can in fact increase it. Look here:

I'm sorry, but as others have pointed out, yes, that background is disturbing. Who the fuck decided not to proof this with someone else before making it public?? I saw it well before I comprehended what the graph was representing and kept going back to it over and over. It is truly AWFUL (sends link to others to rot their brain too)

My Son us 12. He has an IQ of 59, in the mentally retarded range. On one side of the coin he can tell u which day any date falls on, has a huge vocabulary with accurate definitions and spelling. On the other side he can read two paragraphs and not be able to tell you the subject matter. He's also hasn't progressed past basic arithmetic. So, IQ is really a function of what we have decided to weight greatest on our tests. I'm not saying the way we do it is wrong just that intellect comes in many forms.

Douglas R. Hofstadter has a lecture up on Youtube that could be seen as a kind of counterbalance to this discussion. If you are interested in "thinking" and have time to spare, you might find this hour enjoyable:

The success of his gifted students ended up being no differrent then if he had radomly selected 1,000 students and he concluded - "We have seen that intellect and achievement are far from perfectly correlated".

Good heavens, is 130 really all it takes to get into Mensa? That explains a bit.

I went to a Mensa meeting once when I was considering joining. My IQ is well above the requisite 130, and it sounded like it would be interesting to converse with a really intelligent group of people. I found that Mensa is less an organization for the exchange of ideas between exceptionally intelligent people and more a club for people who like other people to know that they're exceptionally intelligent. I passed.

That was exactly my experience as well. I did not renew my membership.

The success of his gifted students ended up being no differrent then if he had radomly selected 1,000 students and he concluded - "We have seen that intellect and achievement are far from perfectly correlated".

My quote (as stated above) has nothing to do with your comment.

Edit: This does not mean that I disagree with you, but as your comment stands, my comment stands.

Good heavens, is 130 really all it takes to get into Mensa? That explains a bit.

I went to a Mensa meeting once when I was considering joining. My IQ is well above the requisite 130, and it sounded like it would be interesting to converse with a really intelligent group of people. I found that Mensa is less an organization for the exchange of ideas between exceptionally intelligent people and more a club for people who like other people to know that they're exceptionally intelligent. I passed.

I've known one Mensa member. He was bright, but not exceptionally so. He seemed to like to talk about being a Mensa member quite a bit.

I've known a couple of Menses (that is the plural, is it not?). 100% of my sample is consistent with your result.

To address a few points in the comments here: a great deal of research has been done on the concept of "intelligence" and the ability of IQ tests to measure the constructs regarded as fundamental to intelligence. Some tests appear to measure these constructs better than others (Wechsler is pretty good at it as is the Stanford-Binet and WJ series). Most of these tests have been standardized and evaluated with fairly large samples (often 5,000+) and hold up pretty well. They also correlate pretty strongly (e.g., r = 0.90) with each other (as should be expected), but because they may be measuring slightly different aspects to intelligence, they don't correlate perfectly.

That said, remember the purpose of these tests is to predict academic achievement, not to set someone on a pedestal for being "smart". They're intended to be used as a diagnostic tool. When a kid is having an unusually difficult time in school, then it is useful to try to figure out what's going on. Part of that may be giving a cognitive test (IQ test) to see if there is an evident deficit in a cognitive process (e.g., working memory, processing speed, etc...).

I find the present study somewhat... well, lacking (just from the summary presented here though). As noted numerous times already, a sample size of 33 students is relatively small, especially compared to the multitude of studies indicating that IQ scores are fairly stable. Some fluctuation is expected, but generally not a "significant" amount (like changing from one category to another). Taking a test more than once, of course, usually results in a higher score as well.

I believe there is an observation selection effect at work in this thread. But that is neither here nor there to the topic.

Quote:

More generally, our results emphasize the possibility that an individual’s intellectual capacity relative to their peers can decrease or increase in the teenage years. This would be encouraging to those whose intellectual potential may improve, and would be a warning that early achievers may not maintain their potential.

This is a money quote! Expressed in other words; even though it is NOT true that any statistical knowledge can be projected as a REAL property of an individual but only a property of the aggregate, it never the less should be interpreted (by the public?) as a property of an individual (yes that is how people interpret it). Read the words in the quote above: "possibility", "can", "would", "may", "would" and "may" in that order.

Sounds kinda shaky, but is the way scientists normally express themselves .. as a vague probability.

Cheers/ StefanC (I am drunk .. sorry .. and English is not my first language)

Multiply the number of students by the number of tests and you get the IQ of anyone who believes the results.

It shouldn't really be about believing the results. One can be skeptical without resorting to belief or disbelief.

How do you come to that conclusion? I mean .. I got my funny hat on and to quote David St. Hubbins, I am better of believing everything I read as opposed to not believing anything at all, because as the dear saint says "this makes me more of an objective person than someone who doesn't believe anything at all".

Kate Shaw Yoshida / Kate is a science writer for Ars Technica. She recently earned a dual Ph.D. in Zoology and Ecology, Evolutionary Biology and Behavior from Michigan State University, studying the social behavior of wild spotted hyenas.